In general, small tubes or hoses having various diameters and made of various materials, which can be used to probe, empty, fill or rinse hollow organs such as, for example, the bladder, stomach, intestine, blood vessels and/or the heart, are referred to as catheters. A special form of intravascularly used catheters, especially for applications in the heart/thorax region, are catheters comprising an electrode which are introduced into primary veins or arteries, such as the femoral vein, for example, and advanced from there to various locations of the heart or in the coronary vessels. These catheters are used to represent or stimulate the electrical activity of the heart or remove regions exhibiting abnormal electrical activity. The latter, which is referred to as ablation therapy, is used as a treatment for cardiac dysrhythmia, for example.
So as to be able to handle such a catheter, the metallic steering cable anchor, which is provided at the distal end of the catheter and designed, for example, as an electrode, is connected to a steering cable, which is typically designed as a pull wire. This steering cable is moved by a plunger, which is arranged at the proximal end of the catheter and extends from the proximal end of the catheter to the distal end. A movement of the plunger in the longitudinal direction with respect to the plunger chamber results in a curvature of the catheter in the central region.
Efforts have been ongoing for quite some time to employ the magnetic resonance imaging (“MRI”) method not only as a diagnostic imaging technique, but also for monitoring the positioning and success of simultaneously conducted catheter procedures, for example, during therapeutic procedures against cardiac dysrhythmia. This necessitates catheter designs that are amagnetic and withstand the stresses of strong alternating electromagnetic fields. In such alternating fields, catheter elements must not shift nor heat up, nor perform mechanical oscillations. Moreover, no catheter-induced image artifacts must occur.
One option to protect an intravascularly used catheter system from the effects of a very strong alternating electromagnetic field is to employ non-metallic materials.
During the attempts to replace metallic elements with non-metallic elements, the observation was made that in manually steerable catheters, notably the metallic steering cable, which acts like an antenna in the alternating electric field, heats up at the ends and is thus not suitable for use in the MRI. If the steering cable is produced of non-metallic materials, especially the design of a reliable, dynamically very resilient connection system to corresponding anchors, for example, the electrode, which is preferably disposed at the distal end of the catheter, is critical for the reliable function of electrophysiological catheters.
A catheter comprising an electrode is known from the document EP 2 275 163 A2. This document describes several options for connecting a tip electrode to a puller wire made of a material such as high molecular density polyethylene. A solution that is shown and described in this document employs a pin projecting from the distal electrode transversely to the longitudinal direction, with the puller wire being wrapped around this pin and the puller wire being fixed thereto. However, the known solution consumes a lot of space because the pin projects perpendicularly to the longitudinal catheter axis. This limits the available space for the electrical and hydraulic lines in the catheter shaft. Moreover, the tensile load applied by the puller wire bends the pin. Additionally, metals are not very resistant to such bending loads, so that the known connection must be considered unreliable.
The present invention is directed toward overcoming one or more of the above-identified problems.